1. Field of the Invention
The present invention relates to a test prod for high-frequency measurement having a contact-side end for electrically contacting planar structures and a cable-side end, in particular a coaxial cable-side end, for connecting to a cable, in particular a coaxial cable, wherein between the contact-side end and the cable-side end a coplanar conductor structure with at least two conductors, in particular three conductors, is arranged, wherein on the coplanar conductor structure a dielectric supporting the coplanar conductor structure is arranged over a predetermined section between the cable-side end and the contact-side end, one-sided or both-sided, wherein the test prod is designed between the dielectric and the contact-side end such that the conductors of the coplanar conductor structure are arranged freely in space and relative to the supporting dielectric in a suspending manner.
2. Description of Related Art
Such a test prod is for example known from DE 199 45 178 A1. This has the advantage that a test prod with impedance control is made available which can be manufactured economically and to high precision, even in mass production, so that minimal reflections occur during contacting with the planar structure for measuring purposes. The arrangement according to the invention is characterized by operating frequencies of up to 40 to 60 GHz or higher, wherein, due to the design according to the invention, the impedance is substantially dispersion-free, i.e., independent of the operating frequency, over the entire coplanar conductor structure. The freely suspended arrangement of the conductors of the coplanar conductor structure between the dielectric and the coaxial cable-side end means that a high contact quality is guaranteed between all conductors of the coplanar conductor structure and corresponding contact points of a device which is to be measured, wherein the contact quality is not sensitive in terms of the test prod being placed at an angle on the contact points of the planar structure.
A shielded microwave test prod is known from U.S. Pat. No. 5,565,788 with an end of a coaxial cable which is connected with probe fingers which form a coplanar conductor with ground probe fingers and a signal probe finger. The ground probe fingers are connected with one another via a shielding element. The shielding element is spaced at a distance from the signal probe finger and arranged between this and the device under test in order to prevent the generation of extraneous signals or parasitic coupling from the device under test which would otherwise degrade measurement accuracy.